//笔试强训_跳台阶

#include <iostream>
using namespace std;

int main() {
    int n;
    while (cin >> n) { // 注意 while 处理多个 case
        int dp[n + 1];
        dp[0] = dp[1] = 1;
        for(int i = 2; i < n + 1; i++)
        {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        cout << dp[n] << endl;
    }
}